Conveyors may be used in stackers to stack material or in devices configured to reclaim material from a stack. Typically, systems designed for stacking and reclaiming material utilize a number of conveyors. One set of conveyors is typically used to convey material to a stacker for stacking in a particular area. Another set of conveyors is used to reclaim the material stacked in that area. Examples of systems used to stack material or reclaim material are disclosed in U.S. Pat. Nos. 7,191,888, 6,782,993, 6,085,890, 5,609,397, 5,562,194, 5,090,549, 4,139,087, 3,604,757, 2,851,150 and 1,996,488, and U.S. Patent Application Publication No. 2007/0102263.
In addition to conveyors, other devices are typically used in stacking and reclamation systems. For instance, a stacker is typically used to stack material transported by a stacking conveyor system. Examples of stackers are disclosed in U.S. Pat. Nos. 3,297,141, 3,653,486, 4,319,677, 4,406,361, 4,629,060, 6,360,876, and 6,896,123.
Conveyor systems used to stack material or reclaim material often include a system of conveying devices. For example, overland conveyors are often used to transport material over relatively long distances to different locations. An overland stacking conveyor may be configured to move material from a material receiving location to a storage pile. An overland reclaiming conveyor may be configured to convey material from a storage area to an area designated for using the material. Typically, a mobile bridge conveyor or other conveyor is positioned adjacent to a stacking overland conveyor. An overland tripper or other device may be configured to feed material from an overland conveyor to the mobile bridge conveyor. The mobile bridge conveyor may stack the material or may move the material to a cross conveyor attached to the mobile bridge conveyor or a stacker for stacking the material.
Often, a mobile bridge conveyor includes and supports a tripper conveyor that is interconnected with a cross conveyor. The tripper conveyor transports material from the mobile bridge conveyor to the cross conveyor. The tripper conveyor typically shares a conveyor belt with the mobile bridge conveyor to lift and convey material. Typically, the tripper conveyor is movably supported on the mobile bridge conveyor to ensure alignment and proper transport of material to the cross conveyor for stacking the material. Misalignment between the tripper and the mobile bridge conveyor can cause significant problems. For instance, due to a misalignment, material may be improperly conveyed or spilled and cause portions of the conveyor belt to be damaged. The cross conveyor is typically affixed to the tripper conveyor to receive material from the tripper conveyor and stack that material in a storage pile adjacent to the mobile bridge conveyor.
Systems that utilize a mobile bridge conveyor that has a tripper conveyor affixed to the cross conveyor are often very heavy due to the structural materials needed to support the material being transported. For instance, tripper conveyors of such devices can weigh 200,000 pounds or more. The tripper conveyor and cross conveyor are typically configured to move along the frame of the mobile bridge conveyor. The tripper conveyor may be attached to the cross conveyor and be supported by wheels that move along rails on the frame of the mobile bridge conveyor. The mobile bridge conveyor must support the tripper conveyor and the cross conveyor attached to the tripper conveyor at numerous different locations along the frame of the mobile bridge conveyor. Because of the size and weight of the tripper conveyor and the cross conveyor and the movability of the tripper conveyor, numerous segments or portions of the mobile bridge conveyor frame must be configured to support the weight of the tripper conveyor and the cross conveyor. Such a requirement typically requires the frame of the mobile bridge conveyor to be over one million pounds.
Conveying devices of such weight are also very expensive. Generally, larger components take longer to design and build than smaller components. Therefore, such devices usually take a relatively long time to fabricate due to the size and weight of the devices and the components being incorporated in such devices.
Moreover, it is relatively expensive to modify such devices to improve the stacking capacity or stacking height such devices may provide. A large part of the expense associated with such modification is usually related to the large size and weight of the components that need to be modified.
Also, such mobile bridge conveyors are typically limited in their applicability for other projects. An owner of such a device may be able to use a mobile bridge conveyor for only one project that may last a set period of time or may only be able to use the device for a certain limited type of projects. However, due to the size and weight of the device and the capabilities of its tripper and cross conveyor devices, it may not be used to meet other needs for the owner.
Additionally, fabrication costs can limit mobile bridge conveyor design options. Typically, mobile bridge conveyors are only sized to be about three meters in width due to extensive shipping costs associated with wider sizes. If shipping is avoided, costly fabrication methods must be used to build a mobile bridge conveyor that is over three meters wide. As a result of this constraint, the maximum width between most tripper conveyor wheels, which are constrained to the mobile bridge conveyor, is about three meters. Such a width constraint may significantly alter the possible design options for a tripper conveyor due to safety and stability issues. Further, the length of the cross conveyor may also be limited due to stability and safety issues.
A conveying system is disclosed in U.S. Pat. No. 7,191,888, which discloses a mobile bridge conveyor and a separate tripper that is movable relative to the mobile bridge conveyor. The movable tripper includes a traveling tripper conveyor and a tipping bridge conveyor. The mobile bridge conveyor and the traveling tripper conveyor share a conveyor belt that travels from the bridge conveyor to the traveling tripper frame. The system disclosed in U.S. Pat. No. 7,191,888 requires the tripper to have a frame that is separate from the bridge conveyor that supports the tripper conveyor and the tipping bridge conveyor, which may also be referred to as a cross conveyor. The tripper may be moved relative to the bridge conveyor to adjust the position of the tripper conveyor and cross conveyor.
Moreover, the position of the mobile bridge conveyor and separate tripper may be adjusted relative to a feed conveyor. To make such an adjustment, the conveyor belt shared by the mobile bridge conveyor and the tripper conveyor of the tripper must be slackened. The slackening of the belt is necessary to avoid belt misalignment that may occur. As a practical matter, the slackening of the shared belt requires operations supported by the mobile bridge conveyor and tripper to be stopped or an auxiliary unit to be operational during this movement. Either alternative incurs significant costs associated with an auxiliary system or the temporarily ceased operations.
A new conveyor apparatus is needed. Preferably, the new conveyor apparatus is configured to reduce conveying down time for adjustments necessary for stacking material and also provides an improved conveying capacity.